Annealing process, &amp;c.



ADOLPH w. MACI-ILET, or ELIZABETH, NEW JERSEY.

ANNEALING- PROCESS, &c.

Specification of Letters Patent.

Patented J une 24;, 191 3.

No Drawing. Original application filed May 25, 1906, Serial No. 818,678. Divided and this application filed May 25, 1910.

- specification.

. This invention relates to annealing metal and other articles, particularly articles which have been formed of steel. i In annealing steel articles, it is important to heat them uniformly, and, particularly when the work is to be nicely done, to permit them to cool very slowly; and it is also important to prevent oxidizing of the articles. In order to secure these and otherobjects, I confine the articles in a retort, which .is placed within a furnace heated by combustion of mixed air and fuel, sealing the retort outside of the furnace, the latter having an opening through which the retort protrudes. Before the articles are hot enough for oxidization, I displace theair from the retort by introducing a gas which will not injure the metal, such for instance as ammonia, or ammonia mixed with a hydrocarbon gas, or a carbonous gas unmixed with ammonia. Other gases may be used. The retort is then heated to the proper point, and preferably rotated during the heating, so as both to heat the retort uniformly throughout, and also to agitate the articles therein so that they shall be uniformly heated; a pyrometer being employed to enable the heat of the articles to be regulated, for some fine work. The retort proper is wholly within the flame chamber of the furnace, so as to insure even heating of the articles therein. The subsequent cooling of the articles is greatly prolonged by reason of the slow radiation of heat from the thickened refractory walls of the furnace, thereby securing a more perfect on Healing of the articles; it being necessary to remove the retort. from the furnace duringv .the cooling operation.

The original body of inert gas remains confined in the furnace during the heating and cooling of the articles, no appreciable or injurious effect being produced thereby on the articles. The articles may be conveniently discharged when hot if desired.

The articles to bc annealed are deposited in bulk within a retort, preferably in the With a valve.

Serial No. 563,286.

. mounted wholly within a flame chamber of a furnace, provided throughout with a refractory lining, all of said lining being usually set in plaster of Paris or asbestos. Any suitable fuel may be consumed in the furnace. Preferably a mixture of hydrocarbon fuel with air is used; the supply of air and fuel being regulated by valves. The air and fuel become mixed within the supply pipes, and the mixture is admitted to burners inserted in openings formed in the o-ppositewalls of the furnace near the top of the flame chamber. The burners point alternately in opposite directions, so as to direct the flames across the top and down around both sides of the retort, and form two sets, extending along the top of the flame chamber above said retort. The gas flames are directed upon and overthe retort and play down around the same and escape through an outlet formed in the bottom of the furnace at the end of the retort, whereby even heating of the latter is assured.

Ammonia or carbonous gas may be supplied from a receiver or generator connected to the retort by means of a pipe provided A gland is used to accommodate the rotation of the retort, since the pipe remains stationary. Threaded into the cover or end of the retort, is a jet or sprayer, having numerous apertures for directing the inert gas in small jets into the retort; said sprayer being connected by the pipe to the gland. The articles are placed in the retort,- and said covers replaced and sealed. Then the inert gas is admitted through the valve, to displace the air from the retort, this being done before the heating of the retort has proceeded very far, so as to avoid oxidizing the articles. The air may escape through a pipe having a valve, which is closed as soon as the attendant observes that nothing but the gas is escaping therethrough. Then the flames at the burners are turned up, and the retort brought to the refquired heat and kept at such heat for the required length of time. Rotation of the retort during the heating operation is effected, whereby the articles are gently agitated, and all portions thereof evenly heated and treated throughout the retort.

In case it is desired to anneal the articles in an atmosphere of ammonia and carbon,

a tank is nearly filled with naphtha. A second tank containing ammonia or other suit able inert gas under pressure is connected with the first tank by means of a pipe, the flow of ammonia being controlled by a valve in said pipe. The latter extends down into the oil tank and terminates near the bottom thereof in a spray. Bubbles of ammonia rise from the spray, and during this action they take up a plenum of naphtha or carbon, filling the top of the tank with gas comprising ammonia and carbon. This gas may be led to the retort.

In annealing steel articles which have been formed by cold forcing processes, such as rolling, drawing, bending, stamping, etc., it is deslrable to fill the retort with a carbonous gas, such for instance, as that which passes through the pipe mentioned. From such gas, the metal will take up a littlecarbon to replace that which has been lost during such forcing processes thus restoring the metal to its original condition at the surface. Moreover the case-hardened or other steel articles are not subject to loss of carbon during annealing. This saving is due to the presence of the atmosphere of carbonous gas, which, if anything, would be more apt to add carbon to the steel than to take carbon therefrom.

This process may be carried out in any suitable apparatus, such for instance, as that disclosed in my copending application No. 318,678, (Patent No. 961,305, granted June 14:, 1910,) of which the present application is a division.

Having thus described my invention, 1 claim:

1. The process of treating steel articles, consisting in heating and agitating them while confined in an atmosphere of gas which is not injurious to the steel, until the articles are annealed;

2. The process of treating steel articles,

consisting in heating and agitating them until annealed and while confined in an atmosphere of gas which is not injurious to the steel, and permitting them to cool slowly.

3. The process of treating steel articles, consisting in heating them while confined in a gas having a carbonous constituent, and agitating them during the heating, until the articles are annealed.

4. The process of treating metal articles, consisting in heating them while confined in a gas having carbonous and ammoniacal constituents, to anneal the articles, and agitating them during the heating, so as to secure uniformity of heating.

5. The process of treating metal articles, consisting in placing them in an iron retort, closing the retort, charging the retort with a mixture of ammonia. and carbonous gas, heating the retort, moving the retort to agitate the articles during the heating until the articles are annealed, and permitting the articles to cool slowly in saidatmosphere.

(3. The process of treating steel articles,

\ which have been forcibly shaped as by drawing, stamping, eto., consisting in heating and agitating the articles until 'they are annealed, while confined in an atmosphere of gas from which the articles take up a plenum of carbon.

7 The process of treating metal articles, consisting in confining the articles in a retort, passing ammonia through naphtha and charging the retort with the resulting mixture, closing the retort so. that it is gastight, simultaneously heating and rotating the retort to anneal the articles uniformly, and slowly cooling the articles in said retort.

ADOLPH W. MACHLET- Witnesses:

JOHN J. Soorr, SAMUEL R. OGDEN; 

